Economies and ecologies of indigenous vs exotic shade trees: experiences from coffee based agro-forestry systems in Kodagu.
The present study was carried out to understand the economies and ecologies of indigenous vs exotic shade trees in coffee agro-forestry system of Kodagu. The primary data was collected from 60 Arabica and 60 Robusta growers between March to April, 2017. On the economic front, the study analyzed the influence of exotic and indigenous shade trees on productivity of coffee. The exotic silver oaks (Grevillea robusta) had adversely impacted productivity of Arabica (Commercially, there are 2 cultivated species of coffee viz., Arabica and Robusta coffee) variety of coffee. In contrast to the this, initially, the number of silver oak trees per ha positively influenced productivity of Robusta. However, further with the increase in number of silver oaks (beyond 121 trees per ha), the productivity of Robusta also declined. The inflection point on the number of silver oaks per ha to the productivity of Robusta was found to be 121 trees per ha. The number of indigenous trees per ha had a positive influence on productivity of Arabica. The dadap trees (Erythrina spp.), generally used as temporary shade in coffee estates, however had a positive influence only on productivity of Arabica. While the redeemed land tenure system significantly influenced the productivity of Robusta coffee. On the ecological front, the study analyzed the influence of indigenous and exotic shade trees on the incidence of White Stem Borer in Arabica. The results found that the incidence of White Stem Borer in Arabica were lower in estates that comprised of higher number of indigenous trees. Though the exotic silver oaks positively influenced the borer attack, was however found to be insignificant. Interestingly, the incidence of borer attack was found to be higher in redeemed Arabica estates. The study recommends the government to re-look into the tree standing rights in the private coffee plantations, encourage more of native shade by supplying indigenous shade tree species to the growers, while also restrict for the limited cultivation of exotic silver oaks in coffee estates.